Primer manufacture



July 3, 1945. c, uss 2,379,450

PRIMER MANUFACTURE Filed June 16, 1942 2 Sheets-Sheet 1 awe/whom H C. ML 7011/ M0555? E51 M KW July 1945. c. w. MUSSER 2,379,450

' PRIMER MANUFACTURE Filed June 16, 1942 2 Sheets-Sheet 2 grvvm'vm C. WAL 701v Mwsm Patented July 3, 1945 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 0. G. 757) Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to a method of producing a mechanical draw piece, more particularly a tion are used to secure the desired flattening of .the head. This latter method requires an addi- To produce flat headed draw pieces by this invention, the piece is cupped and drawn through dies in a conventional manner, and then near the bottom of the draw stroke, brought into contact with a backing punch which flattens the head of the draw piece against the end of the draw punch during the final movement of the draw stroke. The completed flattened draw piece is stripped off the draw punch on its return stroke by the bottom of the die and is ejected by an air blast.

Figs. 1 and 2 show a double acting press which performs the blanking and drawing operations in tional handling and an extra operation. Return- 'ing the draw piece through the die has definite speed limitations and imparts a greater degree of wear .to the die with consequent greater tool maintenance.

The object of the invention is to provide a rapid, single operation method of producing flat headed draw pieces, more particularly primer cups, by the addition of a device easily manufactured and attached to existing draw press equipment; which will not increase the normal die wear and maintenance; which is easily adjusted for variation in thickness and stiffness of stock; and which will produces. more normally uniform draw piece.

Due to the variation and extent of present draw press equipment, the inventive idea involved is capable of receiving a wide variety of mechanicalfaced dies in a separate operation.

Fig. 4 is a detail of a cup and dies, in which the cup head has been flattened in the draw press by dies having curved surfaces.

Fig. 5' is a section through the dies showing the cup near the end of the drawing stroke.

Fig. 6 is a similar view showing the cup contacting the backing member for flattening.

one revolution of the crankshaft I. The blanking and cupping die 2 and the sizing (redrawing) die 3 are held rigidly in the die holder 6 by the die holder plate 1 and cap screws 8. The die holder 6 is fastened to the press 4 by cap screws 5. Cap screws 5 permit alignment of the blanking and cupping die 2 with the blanking punch 9 and the cupping and drawing punch 50. The blanking punch 9 is fastened, through punch holder block It, to the moving ram l2 and actuated in a vertical plane by the connecting rods l 3 journal ed to the crank pins M of crankshaft l.

The blanking punch 9 also acts as a bushing which centers the lower end. of the drawing punch ill in reference to the blanking edge of the blanking punch 9. The draw punch 80 is fastened-t0 the internal ram l5 and is actuated in a vertical plane by the connecting link It journaled to the crank Fig. 7 is a similarview showing the draw punch being withdrawn from the cup, and

Fig. 8 is a similar view showing the finished cup being ejected.

pin ll of the crankshaft l. The crank pins l4 and I! are so spaced, angularly about the shafts axis, that the blanking stroke is completed before the drawing operation is started.

The sizing die support I 8 has an air duct l9 connected to an air line 20. This airline 20 is connected to a compressed air supply and is controlled by a. regulating valve.

In the mechanism which actually does the flattening of the head of the draw piece, a punch guide 2| is fastened by cap screws 22 to the press stand 23. The axis of the backing punch 24 coincides withthe axis ofthe draw punch I 0 and is permitted a small vertical movement by the arcuate plate spring 25 which ha hardened steel bearing plates 26 on each side to protect the adjusting screw 2'! and the end of the backing punch 24. The adjusting screw 21 is retained in adjustment by the locknut 28. I

The lower end of the draw punch Ill is concave I on the draw piece 30 through the elastic recovery of the metal in the head counteracting the deflection it has received in excess of a flat head. When a draw piece is flattened against a flat platen or punch, the elasticity of the metal in the draw piece returns it partially to its original curved contour. This is shown in draw piece 3|, Fig. 3, where a punch 32 enters the cup and presses it against the platen 33. Furthermore, in the case of a separate operation, the side walls frequently tail of perpendicularity with the bottom of the head, as the punch 32 does not become accurately aligned with the draw piece 3| upon entering it.

What is the proper curvature for backing punch 24 depends upon the characteristics of the piece being formed, such as material, thickness,

diameter. etc. and must be determined in each- .from which the draw piece is ejected. The

finished flattened draw piece is carried through this chute 34 to a tray 29.

Actual operations on the work piece at the end of the draw stroke are more clearly illustrated in Figs. 5 to 8. In Fig. tithe primer cup is shown near the end of the draw stroke, but not yet in contact with the backing punch 24. In Fig. 6 it has been carried completely beyond the draw die and flattened by contact with the backing punch. This will have a tendency to spread the side walls so that on the return stroke'Of the draw punch ID, if the-cup does not fall-therefrom by itself, it will be stripped (in contacting the bottom of the draw die. In Fig. 8 the primer die holder plate I. This channel centers the.

stock directly beneath the blanking punch 9 and the draw punch [0. As the crankshaft rotates,

crank pins ll, through connecting links l3, cause ram i 2 to descend. This movement carries the blanking punch 9 into contact with the stock and then with the further completing movement of the crank stroke, stamps out a disk from the stock. With further rotation of the crankshaft, the blanking punch 9 ascends and the draw punch Ill descends to contact the sheared out blank and carries it through the draw die 2 and the sizing die 3.

Nearthe end of the working stroke of the press, the draw piece 30, now completely through the dies 2 and 3 and frictionally held on the draw punch I0, is forced against the backing punch 24. Oncompletion of the draw stroke, suflicien't pressure is built up, through loading of spring 25, to flatten the draw piece between draw punch l0 and the backin punch 24. To secure this required degree of pressure at the lowest portion of the draw stroke, adjustment screw 21 is adjusted and locked in position with the locknut 28.

As draw punch l0 ascends with .continued rotation of shaft I, the bottom of sizing die 3 strips draw piece 30 from the draw punch. Draw piece 30 is then blown by an air blast from the air duct l9, through hole I in the press 'bed and into the chute 28.

Although compressed air has been indicated herein as a means of removing one draw piece before another draw piece is to be flattened,

there are many different mechanical or electrical devices which could be used to secure this result. A movable, pivoted or sliding, lever, or other mechanical device could be synchronized with the press stroke to sweep or deflect the'stripped draw piece 30 into the chute 34 without departing from the basic invention. Other modifications will be evident to those skilled in the art.

I claim:

1. In a machine for forming a flat-headed cup-shaped member out of sheet stock, the com.- bination of a die having input and discharge ends, a draw punch having a working face and being axially movable from a starting position where said face is spaced from said dies input end toward and through said die to a finishing position where said face is more than said cup members length beyond said dies discharge end, means for severing a blank from said stock and for placing said blank'between said draw punch face in its said starting position and the input end of said die, means thereafter effective for moving said draw punch from its said starting position toward its said flnishing position wherea by to force said blank through said die and thereby form it into a cup-shaped member having a rounded head, and a backing punch with a working-face-placed more than said cup member's iength beyond said dies discharge end and. there so restrained that upon advancement of said draw punch to its said finishing position said face of the backing punch contacts the round head of said cup-shaped member and flatten it against'the working face of said draw punch, the said working faces of said draw and backing punches being so oppositely curved that there is set up during said flattening operation a reverse bending in said cup member head which overcomes the elastic recovery tending to round the head. I

2. In a machine for forming aiiat-headed cupshaped member out of sheet stock, the combination of a die having input and discharge ends, a

draw punch having a concavely shaped face and being axially movable from a starting position where said face is spaced from said dies input end toward and through said die to afinishing position where said face is more than saidcup niembers length beyond said dies discharge end,

means for severing a blank from said stock and for placing said blank between said draw punch face in its said starting position and the input end of said die, means thereafter effective for moving said draw punch from its said starting position toward its said finishing position whereby to force said blank through said die and thereby form it into a cup-shaped member having a rounded' head, and a backing punch with a convexly shaped .face placed more than said cup member's length beyond said dies discharge end and there so restrained that upon advancement' of said draw punch to its said finishing position said convex face of the backing punch contacts the round head of said cup-shaped member and flattens it against the said concave face of said draw punch by a reverse bending which overcomes the elastic recovery tending to round the head.

3. In a machine for forming a flat-headed cupshaped member out of sheet stock, the combination of a die having input and discharge ends, a

. draw punch having a concavely shaped face and being axially movable through said die between a starting position spaced from said dies input end and a finishing position spaced more than said cup member's length from said dies output end,

means for severing a blank from said stock and for placing said blank between said draw punch in its said starting position and the input end of said die, means thereafter effective for moving said draw punch toward its said finishing Dosition whereby to force said blank through said I die and thereby form it into a cup-shaped member having a rounded head, a backing punch with a convexly shaped face placed more than said cup member's length beyond said dies discharge end and there so restrained that upon advancetion said convex face of the backing punch contacts the round head of the cup-shaped member and flattens it against the said concave face of said draw punch by a reverse bendingwhich overcomes the elastic recovery tending to round the head, means still later effective for moving said draw punch back through said die to/its said starting position, means including said dies dis-. charge end then operative to strip said cup-shaped' member from said draw punch and thus completely free it on the discharge side of the die,

a and ejecting means effective to move the thus said face is beyond said dies discharge end,' means for severing a blank from said stock and for plac ing said blank between said-draw punch face in its said starting position and the input end of said die, means thereafter efiective for movin ment of said draw punch to its said finishing posisaid draw punch from its said starting position toward its said finishing position whereby to force said blank through said die and thereby form it into a cup-shaped member having a rounded head, and a backing punch with a working force placed beyond said dies discharge end and there so restrained that upon advancement of said draw punch to its said finishing position said face of the backing punch contacts the round head of said cup-shaped member and flattens it against the working. face ofsaid draw punch, the said working faces of said draw and backing punches being so oppositely curved that there is set up during said flattening operation a, reverse bending which overcomes the elastic recovery tending to round the head. a

5. In a machine for forming a flat-headed cupshaped member out of sheet stock, the combination of a die having input and discharge ends, a draw punch having a concavely shaped face and being axially movable from a starting position 'where said face is spaced from said dies input end toward and through said die to a finishing position where said face is beyond said dies dis-f charge end, means for severin a blank from said stock and for placing said blank between said draw punch face in its said starting position and the input end of said die, means thereafter effective for moving said draw punch from its said starting position toward its said finishing position whereby to force said blank through said die and thereby form it into a cup-shaped member having a rounded head, and a backing punch with a convexly shaped face placed beyond said dies discharge end and there so restrained that upon advancement of said drawpunch to its said fin= ishing position said convex face of the backin punch contacts the round head of said cup-shaped member and flattens it against the said concave face of said draw punch by a reverse bending which overcomes the elastic recovery tending to round the head.

C. WALTON MUSSiEiR, 

